12x18 Workshop in NY

rugger8 · January 10, 2013, 03:19:51 PM

Hi everyone. This is my first post, but have been reading a ton on this website. I just received my plans for the the Little House set and there are a number of modifications that I want to do. I will have to get a building permit for this, but want to make sure I have a good idea before I submit the plans. I would like to build a 12x18 workshop that will have a walkable loft for sleeping. It will be around 50 ft. from my current house and will run a 40A breaker to a subpanel in the workshop. The location will be flat for half of it, and then it slopes away fairly steeply. I will detail my plans for each segment below, but please chime in with what I should do as I need the building inspector to sign off on this.

Foundation: plan to do post and pier (Sonotubes w/ reinforced concrete 4' deep). I plan on using 6x6 PT posts on top of Simpson brackets with a "J" bolt in the cement. Plans call for 4x4 posts, but thought it would make sense to go bigger and then just notch the 6x6 posts to accomodate a thru bolt for the main beams. The beams over the front of the building could be 4-6' high due to the slope of the hill. I plan on 6 piling in 2 rows of 3 like the plans and then putting 4x8x18' beams according to plan. (should I upgrade this to 4x10x18 beams?). Separately, I need to do a ridge beam and support that all the way to the ground. Does that mean I need to add to Piers in the middle to support that weight or are the existing beams and piers enough?

Floor: As per plans

Walls: Planning on upgrading to 2x6x10' instead of 2x4x10's. The plan is to put a loft in that is lower than the wall height. Essentially, I want to run 2x6x12' as floor joists across ~1/2 of the length of the building. I plan on supporting these joists by essentially putting a cripple stud underneath each floor joist. Of course, each floor joist will be nailed into the King stud next to it, but also physically supported by the cripple stud it rests upon. I want the bottom of these joists to be at 7'0". This should provide 6'6" of peak headroom in the loft with and 8/12 slope gable roof.

Roof: Can't use Trusses because of loft space and from what I understand, I will need a Ridge Beam and not a Ridge board. So, the load needs to be traced down to the ground. So some help on that would be appreciated. I would plan to use 2x4 collar ties directly underneath the ridge beam on every rafter. The plan calls for 24" O.C. but would like to ask everyone's opinion to moving that to 16" O.C. Also, the plan calls for 12/12 slope, but my understanding is 8/12 slope is walkable and might make that part much easier. This is a tradeoff as the higher slope will give me more headroom. So, for those who have done it, how hard was it to do a 12/12 slope roof on a smallish shed like this. The main question is will my loft design be sufficient to avoid pushing the walls out. IE can I skip the rafter (not sure if this is right word, but bottom third of rafter) ties? And then what should I do for the other portion of the roof that does not have the loft? Put rafter ties in?

Well, those are my main questions right now, but I am sure I will have a number of others as I go through this process. If I can build this way then I get a usable loft at a building height of only 14', so just have to figure out the best way to do this.

Thanks for your help ahead of time!

Jeff

MountainDon · January 10, 2013, 04:06:28 PM

QuoteI will have to get a building permit for this, but want to make sure I have a good idea before I submit the plans.

Hi Jeff,
With that statement in mind, you should go down to the bldg office with some drawings or sketches and ask specifically if they will grant a permit for the building on a pier and beam foundation. If they follow the IRC they may not. Piers combined with drop off slopes can be an idea best not followed.

Yes, a ridge beam would be the way to do the upper floor and roof. Yes, it requires column supports down the the ground, to the foundation.

Rafter spacing and size depends in part on roof loads. Many homes are built on 24" centers.

Anyhow, welcome and before expending much more time on detailing the plans it would be advisable to get the foundation questions answered by the local authorities.

January 10, 2013, 04:32:41 PM

Thanks Don! I hate having to do a permit period, but where I live and the size I would like to make the workshop, I am going to have to go that route. Many sheds this size are just built on skids, so it seems like I should be able to do it because it is essentially the same concept, just beefed up more. I have used the sonotubes for building a deck that was approved by the building department, but obviously, this is a much more significant structure. I will let you know what they have to say.

Jeff

Redoverfarm · January 10, 2013, 06:46:45 PM

. Have you considered a "Gambrel style roof" might be a good choice for a shop and loft.

cholland · January 10, 2013, 10:41:59 PM

For your loft floor consider setting a 1x ledger into the studs. That was a suggested to me by our building dept., following California code. Although this does weaken your wall.

I'm using a parallel chord truss in my build. Eliminates the need for a ridge beam. And you get all the headroom. Need to have them engineered but a truss company should be able to provide that for only a couple hundred.
My whole package is $3600. For a 20x32. Includes the engineering, blocking, all required Simpson brackets, and delivery via crane truck.

January 11, 2013, 09:25:50 AM

Redoverfarm - The Gambrel is great for the headroom and is perfect for the loft space. I have considered it somewhat, but I really like the classic to me look of a Gable. The simplicity in roofing/framing is a plus as well.

Cholland - I had read about cutting a 2x into it, but from my understanding that would weaken the wall too much. I did not think a 1x would be strong enough, but if that passes code, that would be an easier and less expensive way to do it. Do you have any pics of your trusses? I am on a hill so, not sure if I can have them delivered or not. Depends on the declination of the machine. IE, the truck at street level would have to put the trusses 25' below street level. So I originally planned on stick building it.

Jeff

Squirl · January 11, 2013, 10:14:20 AM

I hope you don't mind if I ask the general location of the build? Many of us have built in NY and maybe could give more local knowledge.

The entire building code for the state of NY can be found here:
http://publicecodes.cyberregs.com/st/ny/st/b400v10/index.htm

Post and pier foundations are not specifically allowed, but it is not uncommon for local officials to approve them.
You are right to start your calculations from the top. Roof calculations are simple. Take the square footage times the snow load + the dead weight. 50 pounds per square foot is the snow load in most of New York and the dead weight is usually 10 p.s.f. The ridge beam holds 50% of the roofs weight with 25% falling to each outside wall. If you span the ridgebeam the full 18', you will be beyond the code charts for standard dimensional lumber. You will be in the territory of an engineered piece of lumber, such as an LVL, to pass code.

The complication with ridgebeams is the foundation. All that weight will be falling on a few small points. The size of the footing needs to be able to distribute that to the soil. Soil bearing capacity is usually calculated in pounds per square foot. I usually use 1500-2000 psf, because I have to deal with clay soils, and those are the lowest values, so I will be on the safe side.

BTW

rugger8 · January 11, 2013, 11:52:36 AM

Thanks for the welcome Squirl! I appreciate it.

I live right on the Hudson River about 30 miles North of New York City. The terrain where I plan to build it, about 12' would be flat ground and then the other 6' would start to slope down fairly sharply (30-35 degrees). I think my pilings on that end would be 4-5' high off the ground.

In terms of the weight. If I assume 8/12 slope, that would imply a diagonal lenght of 7.2 ft. per side x 18 ft. length, which is 130 sq. ft. for half a gable roof and 260 sq. ft. total. The 260*(50 p.s.f for snow load + 10 p.s.f.) = 15,600 psf. So, what would that mean in terms of my footing requirement? And also, what would that require for a roof beam? And if I made it smaller, ie 12x16, could I use dimensional lumber at that point?

Jeff

rugger8 · January 11, 2013, 03:08:20 PM

And in terms of the foundation. If post and pier is not allowed, then what are the best alternatives? Cinder block foundation, poured cement? Would prefer to do the work myself as the location is not simple to get to, which makes it more expensive if paying others to do.

Thanks,

Jeff

January 11, 2013, 04:53:24 PM

I spoke with the building inspector today and they are not adverse to the post and pier construction.

His only point is that I will likely have my taxes increased

because it will be considered a permanent structure. He is going to meet with me at my house on Monday to go over some of the options when looking at my sight. So, at least looks like I can keep moving forward. I will try and get some pics of the sight and post them so you guys can see what I am dealing with.

Jeff

rugger8 · January 15, 2013, 09:39:20 AM

Ok, so I met with the building inspector and he seems pretty open to using the sonotubes for footings, which is good. The bad part is there is a hard and fast rule that the max height of the building is 12', starting at the wood floor. Therefore my grand plans of a gable roof with a loft appear to be out. In this case, if I want a loft of any sort, even just for storage, it appears as if I will need to do a Gambrel roof and frame. Any thoughts on this in terms of other options or examples of buildings less than 12' high.

Thanks,

Jeff

Squirl · January 15, 2013, 10:23:40 AM

Well, it looks like all those calculations are probably unnecessary at this point.

Have you considered a 14x24 with a shed or low sloped roof?

It sounds like you will be relegated to a single story. Any building practices, such as trusses or a ridgebeam, to get that extra 1 ft of height to a storage area would probably cost more in money and aggravation per cubic foot of space gain, than just building out.

I haven't heard many people tackling building their own in that area. I look forward to hearing more. My build is in Otsego County.

rugger8 · January 15, 2013, 02:21:48 PM

Unfortunately, i think I am relegated to a single story. Starting to look at Gambrell roofs because then I would at least get to have a small loft area for storage at least. I have not really looked at the shed style in part because I want to minimize the width somewhat and get more of the space from the length. I am enclosing some pics of the site location and if I wanted to do a shed roof, then I would have to turn the shed to face the river. Which now that I think about it, could be really interesting. Have to do some more thinking on it. Essentially, at a 12' height, I have to be 8' off of the property line. I have 100' of property, but my house is on about 50' of it. So, don't want to build too wide so that it is right next to the house. If I build 12' wide, I probably have 25' to the house still. Here are my first pic trys, hope it works. Sorry, was really foggy on the river when I took these, but I have a 3.5 mile water view over the Hudson.

BTW, Building inspector seems pretty lenient, they just don't want people building it as a living space, but for shed it is fine.

Jeff

rugger8 · January 15, 2013, 02:45:37 PM

Just thinking a little bit more outloud. If I go with a shed design and lower the height from 12' to 10', I can be just 6.67 ft. off the property line instead of 8'. So, if I make it 2' wider to 14' I am only losing half foot of incremental yard space, but am gaining a lot in square footage (2'x18'). Squirl, I do like the look of the high ceilings that the shed design gives. What is your total height? But because of my width constriction, I would have to put the skinny end facing the river, when ideally you would want the peak (long end facing the river). I could go wider, but then I don't have any flat level yard anymore and would like to keep some of that.

Jeff

January 15, 2013, 04:29:27 PM

Looks like you need a modern manshed.

http://countryplans.com/smf/index.php?topic=7077.0

I get a lot of use out of mine.

rugger8 · January 15, 2013, 05:12:05 PM

Markert,

Just read through your whole thread, the Manshed looks great!

I have no musical abilities, so won't be doing that, but do want to incorporate an outside fireplace at sometime as well. Can't beat being outside with a fire overlooking a nice body of water. Still up in the air on the design, but am coming around to the shed style. But might make it a tad larger than what you did, since they seem to be letting me.

I will definitely be calling on everyone's expertice here to prevent many of the mistakes I would otherwise make!

Jeff

cholland · January 15, 2013, 06:20:44 PM

Seems like you may be thinking of other ideas now, however to answer your questions.
Yes, it's seems as though a 1x ledger does work, with a 2x6 wall. It still weakens the wall and I decided against it. You of course attach the joists to the studs and it does make for a solid floor. I've seen some pictures on at least one other thread on this site of someone who had done this on a Victorias Cabin build.

For the truss I don't have pics yet, hopefully in about 4 weeks. I'll start a thread of my build soon. I've just been busy. There are also a few pics of parallel chord trusses on this site. You can also do a google search and you'll get the idea. Similar to a scissor truss but better I think. While a crane does make delivery easy. My spec. sheet says they only weigh about 160 lbs. So they could be could be moved by hand with a helper. A little tricky to get up on a wall but it shouldn't require a crane.

rugger8 · January 16, 2013, 01:45:58 PM

Thanks for getting back to me with that info CHolland. Yeah, the loft is definitely out of the question at this point, so on to plan B. But at least I have that info before I start building. Will take a look at the parallel trusses, but probably going another direction.

Jeff

SouthernTier · January 18, 2013, 12:49:06 PM

Quote from: Squirl on January 11, 2013, 10:14:20 AM
I hope you don't mind if I ask the general location of the build? Many of us have built in NY and maybe could give more local knowledge.

The entire building code for the state of NY can be found here:
http://publicecodes.cyberregs.com/st/ny/st/b400v10/index.htm

Post and pier foundations are not specifically allowed, but it is not uncommon for local officials to approve them.
You are right to start your calculations from the top. Roof calculations are simple. Take the square footage times the snow load + the dead weight. 50 pounds per square foot is the snow load in most of New York and the dead weight is usually 10 p.s.f. The ridge beam holds 50% of the roofs weight with 25% falling to each outside wall. If you span the ridgebeam the full 18', you will be beyond the code charts for standard dimensional lumber. You will be in the territory of an engineered piece of lumber, such as an LVL, to pass code.

Another NY builder here (still only the shed so far). Just went through the ridge beam calculation for my planned cabin. Reading through the code (thanks for the link - my hard copy is 2007 and it's good to check what has changed), the live load is actually not exactly the ground snow load (as you say, typically 50 lb/ft2), but actually comes out less when you calculate the roof load. Cuttin'-n-pastin' from the code link: "Ground snow load must be converted to snow load or roof live load for all design methodologies requiring actual "on roof" snow loads. Conversions of "ground" snow load to roof live load, or snow loads are to be made in accordance with all applicable provisions of ASCE-7"

Here's a copy of my conversion calculations. The actual design snow live load is less than the ground load.

rugger8 · February 11, 2013, 02:59:01 PM

Well, still debating which way to go, but am leaning towards the shed design and going 14x18'. I do have a few questions though.

1) With the post and pier design, is it reasonable to do 3 piers per beam or should I do 4 piers? I am thinking of using beams that are 3-2x10x18 with 2 pieces of 1/2 in plywood in between to make a 6x10x18 beam. And is that beam size sufficient?

2) Then for the floor joists, what is sufficient for a 12' span? How much can I cantilever the floor joists over the beam? ie if the total width is 14', should I leave a 1' overhang on each side or can I increase that to 1.5' or 2' overhang to reduce the span. So, would 2x8x14's be sufficient in this arrangement or do I need to go bigger?

3) Roof - How big do the roof rafters need to be to span a 14' length of support (actual length will be slightly longer than that due to a flat roof pitch of 2/14. This is going to be a shed roof with 10' walls on one side and 8' walls on the back creating a pitch of 2' rise over 14' length.

Thanks!

Jeff

February 11, 2013, 04:00:14 PM

Can we refresh the details for those of us who can't recall them exactly....

Snow load is what for the location? PSF Ground load.
NYS snow load map

Just a single story, right?

rugger8 · February 11, 2013, 05:15:36 PM

Sure, the snow load where I am at 30 miles outside of Manhattan is 45 PSF (close to White Plains). And at this point I have switched to a single story shed roof 14x18 ft. With one wall 10 ft. high and the back wall 8 ft. high. So, in addition to my other questions is this enough pitch on the roof or should I make it steeper?

Thanks,

Jeff

MountainDon · February 11, 2013, 05:48:20 PM

I should have caught that and also asked, what type of roofing is being considered; 2/12 is too shallow a pitch for many roofing materials.

rugger8 · February 11, 2013, 06:07:05 PM

I was planning on just using asphalt shingles. I am not in a fire risk area, but it certainly won't shed snow very easily.

Jeff

MountainDon · February 11, 2013, 06:17:18 PM

3) Rafters: 2x8's make it, but only by a little. 2x8 grade #2 spf (spruce-pine -fir) 16"OC will span up to 12'4" using 45 psf (snow) live load. and 15 psf dead load. Other species vary a little
AWC calc

pitch: 2/12 not recommended for shingles. Look into roll roofing perhaps.

2) Floor joist cantilever. By code that is limited to the depth of the material used for the joist.

You can use the same AWC calc for the floor joists span. A lot will depend on what goes into the shed, on the floor and will some of it be concentrated, as in heavy machinery.

1) beam and pier spacing. Gut feeling is that three are two few down an 18 foot length. Tables are in Chapter 5 of the IRC
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_5_par019.htm

The plywood is only spacing material for the hardware; adds no readily computed strength. All splices occur over supports.